Thursday, July 6, 2017

Rare 5.8 earthquake strikes western Montana, the area's strongest temblor in at least 20 years

A rare magnitude 5.8 earthquake has struck western Montana, plunging a
town into darkness and powerful enough to knock down shelves and break
glass, the U.S. Geological Survey said.
Western Montana hasn’t seen an earthquake greater than magnitude 5 in the past 20 years, said USGS geophysicist Robert Sanders.
“It’s not impossible, but it is a very rare event,” Sanders said.
The
earthquake was felt as far away as Spokane, Wash., Boise, Idaho, and
Calgary in Canada, Sanders said. More than 10,000 people reported
feeling the earthquake, with people closest to the epicenter reporting
shaking as strong as intensity level 8 — capable of causing significant
damage.

There were no immediate reports of severe damage, however,
although locals will get a better sense of greater damage after daylight
breaks, Sanders said.

The
earthquake struck at 12:30 a.m. Central Daylight Time Thursday in
Montana, and was followed by at least six aftershocks in the magnitude 3
and 4 range over the next hour. The local sheriff’s office reported
that the town of Lincoln, population 800, was without power. Lincoln is
about three miles away from the epicenter.
A National Weather Service
office in Montana said it had received a report of a gas leak in
Helena, the state capital, and things falling off walls in Great Falls.
Helena was estimated to have a shaking of intensity level 4, or light
shaking that can awaken people and cause dishes and windows to rattle,
causing some to feel as if a heavy truck struck a building.

A
76-year-old resident of Helena, which is about 34 miles away from the
quake’s epicenter, told the Associated Press the earthquake was the
strongest seismic activity that he had ever felt.

Ray Anderson told the AP his wife told him the temblor woke up the dogs.
Thursday’s
Montana earthquake is unrelated to an ongoing earthquake swarm
northwest of Yellowstone Lake, Sanders said. The swarm has been going on
for a little over two months, with the largest a magnitude 4.5. But
most have been very small, recording in magnitude of 0.5 or 0.6, which
are typical in places like Yellowstone every few years, Sanders said.
Yellowstone is home to an active volcano; it last produced a lava flow about 70,000 years ago.